Interactions of WASp, myosin-I, and verprolin with Arp2/3 complex during actin patch assembly in fission yeast

Yeast actin patches are dynamic structures that form at the sites of cell growth and are thought to play a role in endocytosis. We used biochemical analysis and live cell imaging to investigate actin patch assembly in fission yeast Schizosaccharomyces pombe. Patch assembly proceeds via two parallel pathways: one dependent on WASp Wsp1p and verprolin Vrp1p converges with another dependent on class 1 myosin Myo1p to activate the actin-related protein 2/3 (Arp2/3) complex. Wsp1p activates Arp2/3 complex via a conventional mechanism, resulting in branched filaments. Myo1p is a weaker Arp2/3 complex activator that makes unstable branches and is enhanced by verprolin. During patch assembly in vivo, Wsp1p and Vrp1p arrive first independent of Myo1p. Arp2/3 complex associates with nascent activator patches over 6–9 s while remaining stationary. After reaching a maximum concentration, Arp2/3 complex patches move centripetally as activator proteins dissociate. Genetic dependencies of patch formation suggest that patch formation involves cross talk between Myo1p and Wsp1p/Vrp1p pathways

THE CALORIMETRY STUDY OF THE INTERMOLECULAR INTERACTIONS IN THE HETEROGENEOUS SYSTEM THE MAN'S SERUM ALBUMIN - ORGANIC SOLVENT - WATER

The object of investigation: the heterogenous system the man's serum albumin - organic solvent - water. The purpose of the work: the investigation of the power of the formation of the heterogenous systems protein - organic solvent - water; the study of the thermodynamics of the water adsorption in the protein organic media, to be suspended; the determination of the water adsorption insert in the energy, isolating at the insertion of the protein preparation into the organic solvents with the different content of water. For the first time, the calorimetric determination of the enthalpies of formation of the heterogenous systems the protein - organic solvent - water and it has been shown, that the solvatation of water plays the determining role in the influence of nature on the thermodynamic parameters of the water adsorption on the protein in the organic media. The field of application: the physical chemistry of biopolymersAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio